Excessive accumulation of fat induces metabolic disorders. For example, when the fat is accumulated in the liver, muscles and blood to an excessive degree, fatty liver and insulin resistance will be induced. In addition, excessive fat accumulation in the fat cells will result in obesity. An increase in the number of obese people has constituted a serious social problem throughout the world. The accumulation of fat will thus cause various problems as mentioned above, so that it becomes the key to solving the problems to inhibit fat from being accumulated.
For preventing the accumulation of fat, to restrict the volume and kind of diet and to do exercise are found to be effective. However, the restriction of diet and the physical exercise need strong wills and efforts, so that those methods are not always practical for preventing the accumulation of fat. Accordingly, there has been an increasing demand for a method for preventing the accumulation of fat conveniently and effectively without any special exercise and restricted diet. Intake of supplements is now under consideration as one of the means for preventing the accumulation of fat. However, according to the reports about the currently used supplements, some have insufficient efficacy, and others have the potential for impairing the health, for example, impairing the liver function by the administration.
Amino acids are constituents of protein. The amino acids have been found to be highly safe from the long past experience of eating habits. In addition, it has become clear that the amino acids have a variety of physiological actions, in particular, an inhibitory effect on the fat accumulation. There are some reports regarding the mixtures of amino acids. For example, Japanese Patent Unexamined Publication (JP Kokai) Hei 6-24977 discloses that a mixture of thirteen kinds of amino acids can lower the body weight and the body fat; JP Kokai Hei 4-346770 discloses a mixture of eight kinds of essential amino acids can reduce the body fat; and JP Kokai Hei 9-157163 discloses an amino acid composition comprising nine kinds of essential amino acids, with arginine being contained in major proportions, can control obesity. The compositions of those amino-acid mixtures are shown in Table 2. There is also a report about the effect of an amino acid when used by itself, i.e., the promoting effect of leucine on the weight loss when leucine is taken during a period of restricted diet (Nutrition, 2006 May; 22 (5): 520-7). However, the methods disclosed in those documents require exercises or restriction of the food intake. Moreover, the above-mentioned methods are not compared and analyzed in the same manner, so that it has not been identified which composition has an action of sufficiently inhibiting the accumulation of fat. A more effective composition is desired.